An electromechanical relay is an electrically operated mechanical switch. Electromechanical relays may use an electromagnet to move a mechanical component to make or break a conduction path for a signal. Relays may be used to control a radio frequency signal via a control signal. Multiple pole relays may be used to switch a plurality of conduction paths to a common node.
Microwave signals typically are carried on transmission lines. Transmission lines may be coupled to other transmission lines, to electronic devices or to electromechanical relays by connectors. The connectors are designed to minimize signal loss, distortion and impedance mismatches between the coupled transmission lines. However, in general, the longer the length of the transmission line and the more connectors in a signal path, the greater the signal loss, distortion and impedance mismatch.
Multiple pole microwave electromechanical relays may switch a multiplicity of broadband signals to a separate common coaxial transmission line. However, conventional microwave relays are relatively expensive, bulky and require interfaces to separate transmission lines through connectors. Moreover, in coupling to signal paths to be switched, conventional microwave relays require relatively long transmission line lengths and relatively many connectors.
Solid state switching, using solid state transistors in place of electromechanical relays, cannot match the performance of the electromechanical relays for broadband or microwave signals in terms of insertion loss, impedance matching and cross-talk.